[PATCH v3 2/2] sched_ext: Replace use of system_unbound_wq with system_dfl_wq

[Marco Crivellari]

This patch continues the effort to refactor workqueue APIs, which has begun
with the changes introducing new workqueues and a new alloc_workqueue flag:

   commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
   commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")

The point of the refactoring is to eventually alter the default behavior of
workqueues to become unbound by default so that their workload placement is
optimized by the scheduler.

Before that to happen, workqueue users must be converted to the better named
new workqueues with no intended behaviour changes:

   system_wq -> system_percpu_wq
   system_unbound_wq -> system_dfl_wq

This way the old obsolete workqueues (system_wq, system_unbound_wq) can be
removed in the future.

Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@xxxxxxxxxxxxx/
Suggested-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Marco Crivellari <marco.crivellari@xxxxxxxx>
---
 kernel/sched/ext.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 26a6ac2f8826..95791a5ebb0d 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -2765,7 +2765,7 @@ static void scx_watchdog_workfn(struct work_struct *work)
 
 		cond_resched();
 	}
-	queue_delayed_work(system_unbound_wq, to_delayed_work(work),
+	queue_delayed_work(system_dfl_wq, to_delayed_work(work),
 			   READ_ONCE(scx_watchdog_timeout) / 2);
 }
 
@@ -3704,7 +3704,7 @@ static void scx_kobj_release(struct kobject *kobj)
 	struct scx_sched *sch = container_of(kobj, struct scx_sched, kobj);
 
 	INIT_RCU_WORK(&sch->rcu_work, scx_sched_free_rcu_work);
-	queue_rcu_work(system_unbound_wq, &sch->rcu_work);
+	queue_rcu_work(system_dfl_wq, &sch->rcu_work);
 }
 
 static ssize_t scx_attr_ops_show(struct kobject *kobj,
@@ -5087,7 +5087,7 @@ static void scx_enable_workfn(struct kthread_work *work)
 
 	WRITE_ONCE(scx_watchdog_timeout, timeout);
 	WRITE_ONCE(scx_watchdog_timestamp, jiffies);
-	queue_delayed_work(system_unbound_wq, &scx_watchdog_work,
+	queue_delayed_work(system_dfl_wq, &scx_watchdog_work,
 			   READ_ONCE(scx_watchdog_timeout) / 2);
 
 	/*
-- 
2.53.0